Observation of a Lower Bainite Midrib in an Electric Arc Coating Using Scanning Tunnel Microscopy

In this work, a midrib of lower bainite has been observed in an electric arc coating on low-carbon pipe steel using scanning tunnel microscopy. The midrib is a thin strip of ~50–70 nm wide along the direction of acicular bainitic subunit growth, and ~2–5 nm height above the level of surrounding ferrite. An analysis of the cross-sectional profile of the subunit and literature data made it possible to explain the mechanism of bainitic subunit formation.